Genex: Fix segfault when parsing ends with parameter expectation.

The extendResult method expects a non-empty parameters vector, as
assured by the normal case. Avoid calling the method when the parser
finds an incomplete generator expression, but has already entered
the state of expecting to find parameters.
Cygwin: Avoid legacy warnings in RunCMake.* tests

Set the minimum required version of CMake high enough to avoid the
warning for CMAKE_LEGACY_CYGWIN_WIN32.  The warning appears on stderr
and breaks the expected output matching.
Merge topic 'fix-genex-segfault'

36eef30 Genex: Fix segfault when parsing ends with parameter expectation.
Merge topic 'cygwin-RunCMake-tests'

d05a9bd Cygwin: Avoid legacy warnings in RunCMake.* tests